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A New Age for Astronomy: Strangest telescopes in the world – Why are astronomers tracking exotic objects in space by trailing strings under ships and digging holes in Antarctic ice?

By KEAY DAVIDSON

Far below the foam and the freighters, in the pitch blackness and extreme
pressure of the deep Pacific, ghostly particles stream from the ocean floor.
These particles are high-energy neutrinos: subatomic hints of apocalyptic
events occurring millions of light years away.

And dangling from one of the longest pieces of string in the world,
off the coast of Hawaii, is the first of a new generation of huge telescopes
specially designed to explore the world of high-energy neutrinos. This
is DUMAND2, and it has three brothers and sisters round the world: AMANDA
at the South Pole, NESTOR in the Mediterranean near Greece, and NT-36 in
Siberia’s Lake Baikal.

With their long strings of light-detecting devices, lowered into deep
water or ice to wait for the telltale flashes that signal a neutrino,
none of them looks remotely like a conventional telescope. Each of them
will literally look ‘downwards,’ not skywards, to see evidence of neutrinos.
If they looked upwards, they would be overwhelmed by the steady rain of
neutrinos caused by showers of cosmic rays.

By looking downwards, they can use the Earth as a filter to shield them
from this radiation. From their location thousands of feet below the surface
of water or ice, these telescopes will see evidence of neutrinos coming
the other way, through the Earth itself. As these neutrinos pass through
the planet, they interact with atoms, creating muons – positive or negative
particles with a mass much greater than an electron’s. If these muons happen,
in turn, to pass through something dense but transparent, such as water
or ice, they emit flashes of light …